A reliable recognition system is needed that can effectively recognize targets (such as faces, vehicles, animals, etc.) that have been modified to hide their true identity. Some targets of interest may include camouflaged or occluded military installations, weapons and vehicles. Still other targets of interest may include human beings, and in some instances, human faces.
In the field of biometric analysis, denial stands for occlusion, and deception stands for masking. Both denial and deception affect biometric analysis. Biometrics should not assume that the personal signatures are complete and reliable. Occlusion and disguise are not necessarily deliberate. They can also take place in crowded environments, e.g., CCTV when only parts of faces are visible from time to time. Temporal changes can also easily deceive current face recognition engines. Examples of phenomena, with deceptive impact, include bags under the eyes and wrinkles from aging, changes in appearance due to the use of cosmetics, medical condition (injuries and allergies), fatigue, hair style and facial hair. “Our face reflects the lifelong pull of gravity, which lengthens the jaws and deepens orbital bags. In addition people develop fat pads under the eyes, shadows fall differently on the upper and lower eyelid” [1]. Current face recognition systems are ineffective when temporal changes, involuntary or not, occur. In addition, the working hypothesis for the (large) face recognition evaluations carried out so far has not been particularly concerned with the very possibility that targets would seek to deny and/or foil their true biometric signatures. Most clients are legitimate and honest. They have nothing to hide, and have all the incentives to cooperate. The very purpose of biometrics, however, is to provide security from impostors and those seeking to breach security. It is quite obvious that such clients are well motivated to interfere with the proper acquisition of their biometric signatures, and will attempt to hide and/or alter information that is needed for their identification. As occlusion and disguise usually affect only parts of the face.